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Plasmaspheric virtual resonance (PVR) model has been proposed as one of source mechanisms for low‐latitude Pi2 pulsations. Since PVR‐associated Pi2 pulsations are not localized inside the plasmasphere, simultaneous multipoint observations inside and outside the plasmasphere require to test the PVR model. Until now, however, there are few studies using simultaneous multisatellite observations inside and outside the plasmasphere for understanding the radial structure of Pi2 pulsation. In this study, we focus on the Pi2 event observed at low‐latitude Bohyun (BOH, L = 1.35) ground station in South Korea in the postmidnight sector (magnetic local time (MLT) = 3.0) for the interval from 1730 to 1900 UT on 12 March 2013. By using electron density derived from the frequency of the upper hybrid waves detected at Van Allen Probe‐A (VAP‐A) and Van Allen Probe‐B (VAP‐B), the plasmapause is identified. At the time of the Pi2 event, VAP‐A was outside the plasmasphere near midnight (00:55 MLT and L =∼ 6), while VAP‐B was inside the plasmasphere in the postmidnight sector (02:15 MLT and L =∼ 5). VAP‐B observed oscillations in the compressional magnetic field component (Bz) and the dawn‐to‐dusk electric field component (Ey), having high coherence with the BOH Pi2 pulsation in the H component. The H‐Bz and H‐Ey cross phases at VAP‐B inside the plasmasphere were near −180° and −90°, respectively. These phase relationships among Bz, Ey, and H are consistent with a radially standing oscillation of the fundamental mode reported in previous studies. At VAP‐A outside the plasmasphere, Bz oscillations were highly correlated with BOH Pi2 pulsations with ∼−180° phase delay, and the H‐Ey cross phase is near −90°. From these two‐satellite observations, we suggest that the fundamental PVR mode is directly detected by VAP‐A and VAP‐B.

The Huygens Atmospheric Structure Instrument (HASI) detected wavelike temperature fluctuations from 500 to 1,000 km on Titan. However, these fluctuation structures have not been satisfactorily reproduced by any theoretical model to date. In this study, we construct a full‐wave model to simulate the observed gravity wave structure. The model includes dissipation processes due to molecular viscosity, which increases exponentially with altitude, and eddy viscosity, which dominates the lower atmosphere. Using our model, we reproduced the observed temperature perturbations with the superposition of two gravity wave modes, one with λz = 600 km and λx = 1,600 km while the other with λz = 140 km and λx = 8,000 km. We estimate the thermal effects introduced by gravity waves and find that gravity waves below 900 km may significantly modify temperature structure of the upper atmosphere by tens of Kelvins. The wave‐induced thermal effect is sensitive to the eddy viscosity, which controls the dissipation and thermal conductivity below 900 km. When the eddy viscosity is increased by a factor of five, the thermal effect of gravity waves changes from −89 K cooling to nearly zero. This heating mechanism may contribute to the large temperature variability of 60 K in Titan's upper atmosphere.

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